Title Razgradnja farmaceutika u vodi uz nove nanokompozitne fotokatalizatore aktivirane Sunčevim zračenjem Title (english) Degradation of pharmaceuticals in water by novel nanocomposite photocatalysts activated by solar irradiation Author Marin Kovačić Mentor Hrvoje Kušić (mentor)Committee member Ana Lončarić Božić (predsjednik povjerenstva)Committee member Šime Ukić (član povjerenstva)Committee member Urška Lavrenčič Štangar Granter University of Zagreb Defense date and country 2018-07-25, Croatia Scientific / art field, TECHNICAL SCIENCES Universal decimal classificationUDC ) 66 - Chemical technology. Chemical and related industries Abstract Farmaceutici u vodama postaju sve većim problemom današnjice te se intenzivno istražuju načini njihova uklanjanja iz voda. Ispusti iz postrojenja za pročišćavanje komunalnih otpadnih voda identificirani su kao jedan od glavnih puteva ulaska farmaceutika u okoliš. Napredni oksidacijski procesi, poglavito fotokatalitički procesi aktivirani Sunčevim zračenjem predstavljaju potencijalno rješenje problema onečišćenja. Sunčeva energija je besplatan, neograničeni resurs kojeg fotokatalitički procesi trenutno nisu u mogućnosti iskoristiti. Najaktivniji fotokatalizator, prema mnogima u području znanosti i struke, trenutno je
Aeroxide P25 TiO2, međutim aktivan je isključivo u ultraljubičastom području Sunčeva spektra. S obzirom kako UV predstavlja tek 7% ukupnog dijela Sunčeva spektra, jasno je zašto se danas teži razviti nove fotokatalizatore. Među fotokatalizatorima aktivnim pod vidljivom svjetlošću, ističe se SnS2 sa stajališta cijene i (ne)toksičnosti. Međutim, šira primjena ograničena je fotokorozijom, karakterističnom za sulfidne fotokatalizatore. Stoga je istražena mogućnost primjene novoga, nanokompozitnog TiO2–SnS2 fotokatalizatora, koji bi trebao objediniti prednosti pojedinačnih komponenti. Fotokatalizatori SnS2 dobiveni klasičnom precipitacijom, sol-gel i hidrotermalnom metodom su karakterizirani ponajprije FTIR i TGA tehnikama, na temelju koje je ustanovljeno kako SnS2 dobiven precipitacijom SnCl4 i Na2S nema adekvatnu čistoću i toplinsku postojanost za primjenu u fotokatalizi. Sol-gel i hidrotermalni SnS2 te pripadajući kompoziti s TiO2 karakterizirani su XRD, SEM i DRS tehnikama te im je određen pHPZC. Na temelju karakterizacija, pokazalo se kako hidrotermalna sinteza pruža najbolja svojstva. Hidrotermalnom kompozitu (HT) određena je specifična površina B.E.T.-om, poluvodička svojstva EIS-om i Mott-Schottky analizom te uspoređena je s kompozitom sastavljenim od komercijalnih fotokatalizatora,
Aeroxide P25 TiO2 te MKnano MK-900 SnS2. TiO2–SnS2–HT pokazao se superiornim u svakom pogledu prema tehnikama karakterizacije. Ispitana je fotokatalitička aktivnost
TiO2–SnS2–HT za razgradnju farmaceutika diklofenaka i memantina pod simuliranim Sunčevim zračenjem te uspoređena s referentnim Aeroxide P25 fotokatalizatorom. Ustanovljeno je kako je TiO2–SnS2–HT aktivniji za razgradnju diklofenaka, dok je aktivnost za razgradnju memantina manja. Nužnim preduvjetom za dobru fotokatalitičku aktivnost TiO2–SnS2–HT pokazala se adsorpcija onečišćivala. Razlike u adsorpciji diklofenaka i memantina potkrijepljene su DFT računalnim modelom. Ispitana je promjena okolišnih pokazatelja, UOU, KPK, BPK5 te akutne toksičnosti na Vibrio fischeri u fotokatalitičkoj obradi TiO2–SnS2–HT te utjecaj matrice anorganskih soli i složene smjese farmaceutika na učinkovitost procesa solar/TiO2–SnS2–HT. Istražena je i mogućnost dugotrajne primjene u ponovljenim ciklusima fotokatalitičke obrade te mogućnost obnove fotokatalitičke aktivnosti toplinskom i kemijskom reaktivacijom, odnosno ozonacijom. Rezultati ukazuju na potrebu za reaktivacijom uslijed smanjenja konverzije diklofenaka te pogoršanja okolišnih pokazatelja. Reaktivacijom se obnovio znatan dio aktivnosti, međutim dio se nepovratno izgubio uslijed oksidacije SnS2 tijekom reaktivacije.
Abstract (english) Pharmaceuticals in water are a growing cause for concern today. Currently intense research is under way to find appropriate means for their removal. Effluents of wastewater treatment plants are prime sources of pharmaceuticals in the environment. Among them, advanced oxidation processes, especially photocatalytic processes active under solar irradiation represent a viable solution. Solar energy is a free and abundant resource, which is not currently utilized to its full extent in photocatalysis. Aeroxide P25, regarded as the photocatalyst with highest activity by many experts in the field, is active only in the ultraviolet spectrum. Since UV represents only 7% of the total solar spectrum, one can easily understand why research on solar active photocatalysts is a current topic. SnS2 is one of such solar active photocatalysts, also inexpensive and non-toxic, however its widespread application is hindered by photocorrosion. Hence the feasibility of a TiO2–SnS2 nanocomposite photocatalyst was investigated, which could possibly gain advantages of both independent components; i.e. achieve higher stability and limit photocorrosion.
SnS2 obtained by conventional precipitation, sol-gel and hydrothermal methods were characterized foremost by FTIR and TGA techniques. On the basis of these analyses, SnS2 obtained by conventional precipitation, from SnCl4 and Na2S precursors, was omitted from further investigations due to low purity and thermal stability. Sol-gel and hydrothermal SnS2, with their respective TiO2 composites, were characterized by XRD, SEM and DRS techniques, along with the determination of their pHPZC. Hydrothermal synthesis has shown to provide the best properties. The hydrothermal composite was characterized by B.E.T., along with semiconductor properties by EIS and Mott Schottky analysis and compared to a composite prepared from commercial photocatalysts, Aeroxide P25 and
mkNano MK-900 SnS2. TiO2–SnS2–HT has shown superior properties in all aspects.
The photocatalytic activity of TiO2–SnS2–HT for the degradation of pharmaceuticals diclofenac and memantine under simulated solar irradiation was investigated and compared with Aeroxide P25 for reference. TiO2–SnS2–HT has shown to be more active for diclofenac degradation, however that was not the case for memantine. Adsorption was established to be the most important factor in achieving good performance with TiO2–SnS2–HT.
DFT computational models were applied to explain differences in adsorption. Changes in environmental parameters, such as TOC, COD, BOD5 and acute toxicity on Vibrio fischeri were monitored in photocatalytic treatment of diclofenac. Long-term application stability and the need for reactivation was investigated in successive cycles of diclofenac degradation. The need for reactivation was clearly evident, due to accumulation of adsorbed DCF and degradation byproducts, causing deterioration of environmental parameters in successive cycles. Thermal and chemical reactivation were investigated for the reactivation of
TiO2–SnS2–HT. While photocatalytic activity was restored to a great extent, some of the activity was irreversibly lost due to oxidation of SnS2.
Keywords
diklofenak
fotokataliza
memantin
nanokompozit
okolišni pokazatelji
reaktivacija
solar
TiO2-SnS2
Keywords (english)
diclofenac
photocatalysis
memantine
nanocomposite
environmental aspects
reactivation
solar
TiO2-SnS2
Language croatian URN:NBN urn:nbn:hr:149:155672 Promotion 2018 Project Number: UIP-2013-11-7900 Study programme Title: Chemical Engineering and Applied Chemistry - Doctoral course Type of resource Text Extent 175 str. ; 30 cm File origin Born digital Access conditions Open access Terms of use Created on 2023-08-29 10:26:43
